Abdominal Aortic Aneurysm (AAA)

General Information

Classification: Cardiovascular

What is it?

High morbidity enlargement and dilation of a region of the abdominal aorta (150% of normal diameter), with risk of rupture proportional to size

Risk Factors: atherosclerosis*, white male, smoking, older age (>60), high BP/cholesterol/obesity, history of aortic dissection (AD)

Small AAAs are classified as 3-5cm, with the rate of rupture increasing significantly for every size increase

Saccular (localized) vs Fusiform (circumferential)

Evaluation:

  • Enlargement rate
    • 0.2/0.3cm per year
  • Symptoms
    • Majority of afflicted individuals are asymptomatic
    • Shock, abdominal pain, distension
    • If ruptured: gastrointestinal (GI) bleeding, CHF

Pathophysiology & Etiology

  • Primarily due to weakness in structural integrity of aorta (e.g., elastin, collagen)
  • Thus, the infrarenal region may be more likely to be compromised because it has a lower number of collagenous lamellar units
Anatomical Blurb: Aorta Anatomy

The aorta, the strongest and largest artery in the body, is divided into subcomponents from its origination at the left ventricle (and the aortic valve).

  1. The aortic arch: the ascending and descending aorta (subclavian, carotids, and brachiocephalic trunk originate here)
  2. The thoracic aorta: chest cavity (wall, esophagus, bronchi)
  3. The abdominal aorta: supplies abdominal organs (stomach, intestines, kidneys, liver, etc)

    Treatment

    CT scan of abdominal aortic aneurysm (AAA) (OpenI, NLM)

    Surgical approach

    Recommended for non-ruptured aneurysms <5-5.5cm, or when they become symptomatic

    Endovascular repair/EVAR (using femoral artery), open repair (graft affected aortic region)

    Non-surgical approach

    For small aneurysms, can introduce lifestyle modifications: control BP and cholesterol, exercise, diet

    Physiological Blurb: Aneurysms

    Aneurysms are expanded and bulging blood vessels, that may have high risk of rupturing.

    Complications: blood stasis promotes thrombi or emboli formation, life-threatening hemorrhage, related organ/tissue damage

      Potential complications: ischemia, MI, amputation, death, impotence, surgical complications (vascular injury or nicking, breakdown of graft material), renal insufficiency

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